Method of vibrating a mold case

ABSTRACT

The outer steel shell or case of a mold for casting concrete pipe having a gate and vibrators mounted on the gate with their axes of rotation normal to the axis of the case and outside the case.

United States Patent 1 v [111' 3,711,587.

OConno'r et al. 7 [451 Jan. 16, 1973 [54] METHOD OF VIBRATING A MOLD [56] I I References Cited CASE . UNlTED STATES PATENTS [75] Inventors: James F; OConnor, Long Beach;

Gordon J, Black, Nuevo, both of 2,969,575 l/l96l Gagne .25/4l JUX Calif 1,873,4l3 8/l932 Jackson ..25/4l J X 2,869,213 H1959 Longfellow ..249/173 [73] Assignee: Ameron, ln'c., Monterey Park, Calif. [22] Filed: Feb. 26, 1971 Primary Examiner-Robert F. White Assistant ExaminerAllen M. Sokal 21 A N .1 l 1 pp] 0 19,314 Attorney-Christie, Parker & Hale Related US. Application Data [62] Division of Ser. No. 732,335, May 27, 1968 Pat. No. [57] ABSTRACT 3,611,516- r The outer steel shell or case of a mold for casting concrete pipe having a gate and vibrators mounted on [52] US. Cl ..264/7l the gate with their axes f rotation normal to i 1 1 i "1328b 21/14 of the case and outside the case. [58] Field of Search ..264/7l; 25/30 R, 127, 41 J 1 Claim, 7 Drawing Figures m i f i2 Q4 Q3 H 1 l 3 s F 4 V /IG #3 J L .3 w 2| i 7 Ii IIS IE v 1 METHOD OF VIBRATING A MOLD CASE CROSS-REFERENCE TO RELATED APPLICATION This is a division of our copending application Ser. No. 732,335, filed May 27, 1968 now u.s. Pat. No. 3,61 1,516.

' BACKGROUND OF THE INVENTION 1. Field of the Invention This invention has to do generally with the field of molding concrete pipe in steel shell molds and more particularly with the art of vibrating the outershell or case of the mold as the concrete is fed into the mold and for a period thereafter to facilitate filling the mold and to compact the concrete therein.

2. Description of the Prior Art Heretofore vibrators have been mounted at random positions on the case by means of brackets which in turn are welded to the thin-walled shell. This results in undue localizing of the vibrations and hence a multiplicity of vibrators are required in order to distribute the vibrations throughout the shell with sufficient amplitude to accomplish the desired purpose. A more series consequence of this, however, has been the concentration of stress forces in localized areas of the shell causing fatigue of the metal and the early failure of the mountings and the shell itself by the cracking of the shell and the mountings. The gate, being a heavy mass extending the full length of the case, acts as a dampener as the vibratory waves come to it.

SUMMARY OF THE INVENTION The present invention provides for the mounting of only a minimum number of vibrators on the gate of the case or shell, or on a longitudinal beam, and the mounting of these in a manner such that the axis of rotation of the vibrator is normal to the longitudinal axis of the shell and completely outside the shell. It has been found through thorough experimentation that considerably fewer vibrators are required to compact the concrete since better distribution of the vibrations throughout the mold case is achieved. It has also been found that the method disclosed herein overcomes the cracking and failure of the case and mountings. With 4 the old-type mountings the case developed cracks within a few weeks and had to be repaired. With the present mounting, cases have been used for several months without failure.

It is believed that the mounting of the vibrators on the gate (or on a beam) results in the gate acting as a force distribution beam which tends to spread the vibrator forces over the entire length of the form. Also, with the vibrators mounted with their axes of rotation normal to the longitudinal-axis of the form and outside the form, the effective force of each vibrator is radial to the form and the gate thus moves radially in and out and induces waves in the case skin that continue circumferentially from the gate. 6

Thus an object of the inventionis to provide a novel and improved mold case and vibrator assembly in which the mold case embodies a novel vibrator mounting means thereon designed .to achieve vibration of the case for compacting concrete and yet results in long 65 wear of the case without undue fatigue thereof. It is also an object to provide a novel method of vibrating the case.

A further object is to provide a novel mounting for a vibrator on a-mold case and to provide a novel case.

BRIEF DESCRIPTION OF THE DRAWINGS These and other aspects of the invention will be more fully understood by referring to the accompanying drawings, in which:

FIG. 1 is an elevational view, partly in section, of a mold for casting concrete pipe or the like;

FIG. 2 is a cross-sectional view on line 2-2 of FIG. 1, but on a smaller scale;

FIG. 3 is a fragmentary sectional view on line 3-3 of FIG. 1, but on a larger scale;

FIG. 4 is a fragmentary sectional view on line 4--4 of FIG. I, but on a larger scale;

FIG. 5 is a fragmentary face view on line 5-5 of FIG. 4 as it would appear with the vibrator removed;

FIG. 6 is a fragmentary sectional view on line 66 of FIG. 1, but on the same scale as FIG. 4; and

FIG. 7 is a diagrammatic view of a mold showing an alternate form of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS More particularly describing the invention, in FIG. 1 we show a mold 11 for the casting of concrete pipe or the like wherein the concrete is poured into the top of the mold and the mold vibrated to assist in the pouring and compaction of the concrete. The mold has an outer case or shell 12 with which we are chiefly concerned, an inner wall 13 which defines the inner wall of the pipe and suitable annular end ring assemblies at the top and bottom 14 and 15, respectively, holding the shells in concentric relation and enclosing the annular space 16 at the bottom. Concrete 17 which will form a pipe having'a cylindrical wall reinforcement 18 is shown in the mold.

Heretofore molds of this type had been vibrated by the mounting of vibrators of the rotary, air-driven type at random positions over the outer case or shell 12, but this has resulted in fatigue of the metal and cracking of the case over very short periods of use. In the present invention the vibrators, designated V, are mounted along the mold gate 21.

The outer case or shell 12 comprises a thin sheet of steel which is substantially circular. This has at least one longitudinal split or parting, depending upon the diameter, and the one shown is provided with one such parting 22 defined by the two substantially rigid gate members 23 and 24. These are recessed at 26 to receive the edge portions 12' of the shell 12 and the parts are securely welded together. The adjacent edges of members 23 and 24 may be shaped to be complementary, as shown (FIG. 4), and one edge recessed at 28 to accommodate a gasket 29.

Each gate member is provided with a longitudinally extending bar which is welded thereto. Thus gate member 23 has an angle bar 31 of L-shape in cross-sec- 0 tion and member 24 has a flat bar 32. The bars are provided with registering holes 33 and 34 (FIG. 6), respectively, spaced longitudinally of the bars for the reception of bolts 35 fitted with nuts 36 which serve to releasably secure the parts in tight-fitting relation. Holes 37 in bar 32 give access to nuts 46. Webs 38 and 39 welded at intervals along the bars 31 and 32, respectively, and the respective gate members lend strength and rigidity to the structure. The short section 31' of bar 31 extends toward bar 32 and abuts the same when the partsare secured by bolts 35, creating a fulcrum action and insuring the tight-sealing of gate members 23 and 24 on gasket 29.

It is a particular feature of the invention that the vibrators V are rigidly mounted on the gate and this is accomplished by means of a special bracket 40 for each vibrator. The bracket comprises a solid member of T- shape in cross-section, having a main section or base 42 to which the base 43 of the vibrator is bolted and which in turn is secured to the section 31 of bar 31 of the gate by bolts 45 and nuts 46, which retain vibrator and bracket when the gate is opened for stripping, and a central section 47 normal thereto which is secured to the main portion of bar 31 by bolts 35 and nuts 36'. Webs 48 are provided at intervals to strengthen the bracket and provide rigidity. Bolts 45 and nuts 46 also serve to secure the vibrator to the bracket 40.

The vibrators are so mounted that their axes of rotation are normal to the longitudinal axis of the shell and outside of the shell, or parallel to a linetangent to the shell at the gate. Thus, the axis of the vibrator shown in FIG. 3 is along the broken line 50. With this construction the effective force of the vibrators is an oscillating movement radial to the mold which moves the gate in and out and induces waves in the case skin that travel circumferentially in both directions from the gate. For extremely large-diameter forms having more than one gate, vibrators would be mounted on each gate. The vibrators themselves are of a standard air-driven type and, by way of example, may be so-called Vibrolaters" of a type offered for sale by Martin Engineering Co. The cycle of frequency of vibration may be in the range of 6,000 to 10,000 c.p.m., although this is not intended as a limitation on the frequency range. Normally the average frequency is about 8,000 c.p.m.

While the construction shown and described is a preferred one, we contemplate that, alternately, the mold might be vibrated from the inside with vibrators attached to the inner wall of the mold. Thus, by way of example, in FIG. 7, we show diagrammatically in crosssection a mold 55 with an outer shell 56 and an inner wall 58. The latter has a gate 59, but since this is usually of much lighter construction than the gate on the outer shell, we propose to provide a longitudinal beam or bar 60 welded or otherwise rigidly attached to the inner shell or wall 58 and bolt the vibrators V to the beam, either directly or by intervening brackets, at spaced positions along the beam. Preferably the beam should be spaced circumferentially from the gate 59. The axes of rotation of the vibrators would be normal to a plane extending longitudinally of the inner shell and radially thereof through the beam.

Although we have illustrated and described preferred forms of our invention, we contemplate that various changes and modifications can be made therein without departing from the invention, the scope of which is indicated by the following claims. For example, in the case of mounting vibrators on the outer shell a separate beam might be used in place of the gate, in much the same manner as suggested for the inner shell.

We claim:

1. The method of vibrating a mold for concrete pipe or the like having an outer case comprising a thin shell with a longitudinal split, and separate re atively l'lgld gate members extending longitudinally of the shell and rigidly secured to each edge of the shell, the method comprising securing the gate members together so that adjacent longitudinal edges of the gate members are held rigidly together by longitudinally spaced securing means positioned so each gate member is continuous between adjacent securing means so the gate members form an integral stiff beam extending longitudinally along the split, pouring concrete into the case, and vibrating the stiff beam radially of the case by rotating a set of rotary vibrators secured to the beam with their axes of rotation normal to the axis of the shell to induce waves in the beam so it will spread the forces generated by the waves throughout the shell to compact the concrete. 

